Patent GB-1220011-A (GB)
Title: A remote control system and apparatus for responding to predetermined impulse patterns
IPC: H04Q9/14
Filed: 1969-03-26
Abstract: 1,220,011. Electric signalling. ZELLWEGER Ltd. USTER FACTORIES FOR APPARATUS & MACHINES. 26 March, 1969 [26 April, 1968], No. 15732/69. Heading G4H. In apparatus for transmitting a command signal of the kind in which a single command is sent in each operating cycle of the transmitter, a pilot pulse triggers a silicon controlled rectifier 101 into its conductive state to cause a synchronous motor 9 to start and rotate a number of coded-gap switches, the rectifier 101 remaining in its conductive state only if the received pulse pattern agrees with the switching pattern of the gap switches, the gap switches, at the end of the pulse pattern, serving to connect the rectifier to actuate a relay 106 to cause the command to be performed, after which the gap switches are returned to the rest position, thereby resetting the rectifier 101 to its non-conductive state. The signals are transmitted over the power lines by audiofrequency pulses superimposed on the mains voltage. These pulses are converted to D.C. in a receiving section 11 and applied to charge a capacitor 16. The start or pilot pulse causes a signal from the capacitor to be applied via contact I of the coded-gap switch via resistor 23, line 34 and resistor 108 to fire the SCR 101. This conducts and takes current from rectifier 7 through resistor 105 and 107. The load on the rectifier draws current from the main supply through switches 30 and 28 and the synchronous motor 9, which accordingly starts running. Switches 28 and 30 change over as the motor moves from the rest position and mains voltage is applied to keep the motor running through switch 28 and resistor 21. The rectifier is directly connected to the mains through switch 30. As switch 30 changes the rectifier voltage collapses and the SCR 101 is extinguished. Contact finger 25 passes over contact II shorting out the capacitor and discharging it. The contact finger 111 of switch 110 briefly touches contact 109 causing the SCR to refire. As the motor rotates switches 112 and 113 change over at predetermined times. If the receiver unit 100 is arranged to respond to a pulse in the first interval the switch 112 makes with contact I in this interval. If a pulse is received in this interval the capacitor is charged and discharges through contact V of switch 24, contact I of switch 122, contact I of switch 114 and the input 102 of SCR 101 which remains fired. The current is insufficient to operate relay 106. If no pulse had been received in the first interval, the SCR 101 would have extinguished. After leaving contact V switch 24 passes over contact IV to discharge the capacitor 16. If the receiver is set to respond to the absence of a pulse in the second interval the switch 112 is on contact III. The capacitor is connected via contact V of switch 24 to the output 103 of SCR 101 whereby it is negatively charged. If no pulse is received in this interval the SCR remains fired. If a pulse is received the positive charge applied to capacitor 16 cancels the negative voltage at output 103 and causes the SCR to extinguish. The process continues for ten intervals at the end of which switch 110 makes with contact III shorting out resistor 105 so that a heavier current passes through SCR 101 to operate relay 106 to effect the desired control, e.g. to switch on a heating circuit. The relay changes over switch 122 so that switch 133 is connected to line 27 instead of switch 112. The unit then responds to a different pulse sequence to switch off the heating circuit. The motor 9 then returns the switches to their rest position. Switch 30 returns to position I briefly deenergizing rectifier 7 and extinguishing SCR 101. Other controls may be effected by other units, e.g. 200. The switches 24, 28 and 30 are formed by conductive tracks on a drum member 50, Fig. 2, the tracks co-operating with contact fingers as shown. The drums are slotted and retained on the drive shaft 42 by bars 53 and keys 52. The switches 110, 112 and 113 are formed by tracks on a drum 150 with cooperating contact fingers. The drums may readily be changed to cause the unit to respond to a different pulse sequence.